1. Field of the Invention
The present invention relates to a method of arranging mask patterns, more particularly, to a method of arranging several mask patterns have different corresponding positions with lenses to lessen the lens mura of the panel.
2. Description of the Prior Art
In an exposure process, a light source of a scan exposure apparatus produces exposure light, like i-line, KrF, ArF, etc. The light passes through a mask and a projection lens to project on a photoresist of a semiconductor wafer or a glass substrate. The circuit pattern on the mask is transferred to the planned section of the substrate (called “a scan”) to be a hard mask of the etching or the ion implanting. Then, the plate stage or the mask stage of the scan exposure apparatus moves toward the next position and repeats the same exposure, and the pattern of the mask is transferred to the photo-resist of the whole substrate step by step.
Recently, the size of LCD and PDP monitors have become bigger and bigger, and the size of the mask have become bigger, too. Therefore, the lenses of the recent exposure apparatus are combined by a plurality of lenses. The pattern of the mask is transferred to the glass substrate in the ratio of 1:1. However, every lens has a slight difference, lenses have overlapping sections, or the projection lenses have a precision bias after a long period of use.
Please refer to FIG. 1. FIG. 1 is schematic diagram of a corresponding position of a mask pattern and a lens of an exposure apparatus according to the prior art. The five masks in FIG. 1 are the exposure masks in the general TFT LCD manufacture process. The five masks are individually the gate electrode (GE) mask I, the semiconductor (SE) mask II, the source/drain (SD) mask III, the contact hole(CH) mask IV, and the pixel electrode (PE) mask V. Each of them has a corresponding mask pattern 102, 104, 106, 108, and 110 on the center of the masks I, II, III, IV, and V. All of the five masks I, II, III, IV, V have the width of L, and the mask patterns 102, 104, 106, 108, 110 have the width of I respectively.
Please note that, lenses of the exposure apparatus usually have n lenses, and the lens and the adjacent lens intercross and have a lens overlapping section. Hence, FIG. 1 illustrates the masks I, II, III, IV and V in the exposure apparatus, the corresponding position of each lens overlapping section 112, 114, 116, 118 and 120, the mask patterns 102, 104, 106, 108 and 110, and the masks I, II, III, IV and V. The distances of the mask patterns 102, 104, 106, 108 and 110 with the lens overlapping sections 112, 114, 116, 118 and 120 are z. The distance of the boundary of the masks I, II, III, IV and V with the boundary of the mask patterns 102, 104, 106, 108 and 110 are A for clear illustration in the prior art. But, the distance of the boundary of the mask and the boundary of the mask pattern isn't a fixed width in real manufacture.
Please refer to FIG. 2. FIG. 2 is a schematic diagram of photoresist patterns after exposure of the mask patterns of FIG. 1. FIG. 2 continues the condition of FIG. 1. Photoresist layers I′, II′, III′, IV′, and V′ are the schematic diagrams of the masks I, II, III, IV and V exposure on the glass panel. That means following the process of the scanning exposure apparatus, one section of the glass panel will be exposed by the masks I, II, III, IV and V in sequence. Therefore, in FIG. 2, the photoresist layers I′, II′, III′, IV′, V′ and the photoresist patterns 202, 204, 206, 208, 210 individually show the diagrams of the masks I, II, III, IV, V and the mask patterns 102, 104, 106, 108, 110 exposed on the glass panel.
As an example of the ratio 1:1, after completing many PEPs (photo-etching-processes), the width of the photoresist layers I′, II′, III′, IV′, V′ are L, and the width of the photoresist patterns 202, 204, 206, 208, 210 are I. The distances of the boundaries of photoresist layer I′, II′, III′, IV′, V′ and the boundaries of photoresist patterns 202, 204, 206, 208, 210 are A as the distance of the boundaries of the masks I, II, III, IV, V and the boundaries of the boundaries of the mask patterns 102, 104, 106, 108, 110. The distances of the photoresist patterns 202, 204, 206, 208, 210 with the lens sections 212, 214, 216, 218, 220 are z as the distance of the mask patterns 102, 104, 106, 108, 110 with the lens overlapping sections 112 , 114, 116, 118, 120. Finally, every lens section 212, 214, 216, 218, 220 is in the same position of the photoresist layer I′, II′, III′, IV′, V′.
Please refer to FIG. 3. FIG. 3 is schematic diagram of transfer patterns of FIG. 2 after exposure. As FIG. 3 shows, glass panel 302 has a plurality of transfer patterns 304. Each transfer pattern 304 is exposed by the above-mentioned five masks in the same section of the glass panel 302. That is why every lens overlapping section 212, 214, 216, 218, 220 in FIG. 2 is in the same position of the photoresist layers I′, II′, III′, IV′, V′ and the photoresist patterns 202, 204, 206, 208, 210. And, each transfer pattern 304 on the glass panel 302 has an obvious lens mura 306.
As mentioned above, because of the precision bias after a long period of use, the lenses overlapping sections of the prior art exposure apparatus become the uniformity of the exposure light from each lens. So, in the prior art, after many mask exposures, the many PEP is complete, and the monitor has various critical dimensions (CD) and overlays in a few sections of the panel. The monitor has lens mura. The quality of the product drops, and the yield of manufacture decreases. Therefore, to solve the lens mura problem is an important issue.